(a) Field of the Invention
The present invention relates to electric shutters and more particularly to improvements in a controlling circuit adapted to an electric shutter of a type wherein a shutter closing operation is started by passing an electric current to a driving coil.
(B) Description of the Prior Art
In a photographic camera in which this kind of shutter is incorporated, unless a current source is kept connected to an operation controlling circuit until an exposing operation ends, a trouble will be caused. That is to say, if the current source is cut off the operation controlling circuit in the course of the exposing operation, a controlling signal to pass a current to a driving coil (such as an electromagnet, plunger or solenoid) to start a shutter closing operation will not be issued forever and the shutter will remain open. Therefore, as a result, not only the film frame exposed by that time but also the film frame in case the film is then wound up will be spoiled. Such matter will be likely to occur in case a comparatively dark object is to be photographed.